A CONTRIBUTION TO THE OOLITE PROBLEM 



FRANCIS M. VAN TUYL 

 University of Illinois 



INTRODUCTION 



At the present time there are two prevalent theories of oolite 

 formation, namely, the inorganic, or chemical precipitation theory, 

 and the organic theory. Prior to the year 1890 the inorganic theory 

 was generally agreed to and it is to this day the most widely accepted 

 of the two. 



In the year mentioned, however, Wethered 1 pointed out a close 

 relationship between the concretionary structure of the calcareous 

 algae Girvanella and that of true oolite, and showed that certain 

 so-called oolites of the Carboniferous and Jurassic of England really 

 consist, in part at least, of rounded calcareous masses secreted by 

 this organism, since they possess in addition to the concretionary 

 structure the vermiform tubules which characterize the genus. But 

 in this and again in a succeeding paper, entitled "The Formation 

 of Oolite," which appeared in 1895, 2 Wethered was unable to demon- 

 strate the presence of the Girvanella tubules in typical oolite spher- 

 ules showing both radial and concentric structure, although he was 

 led to believe that these were also of algal origin. 



Following closely upon Wethered as a champion of the organic 

 theory came Rothpletz, who published a paper on the origin of 

 oolite in 1892. 3 This investigator upon studying the recent oolites 

 of Great Salt Lake found that where these were still in the water 

 they were usually covered by a bluish-green algal mass consisting 

 of the cells of Gloeocapsa and Gloeothece, forms which are known to 

 secrete carbonate of lime; and, when the oolite grains and rodlike 



1 Quar. Jour. Geol. Soc. London, XL VI, 270-83. 



2 Ibid., LI, 196-209. 



*Botanisches Centralblatt, No. 35, pp. 265-68 (English translation by F.W. Cragin, 

 American Geologist, X, 279-82). 



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